Image capture device, pixel, and method providing improved phase detection auto-focus performance

ABSTRACT

An image capture device, pixel, and method of determining a focus setting for an image capture device are described. The image capture device includes an imaging area and a pixel readout circuit. The imaging area includes a plurality of pixels. The plurality of pixels includes multiple pixels in which each pixel of the multiple pixels includes a two-dimensional array of photodetectors and a microlens. Each photodetector in the array of photodetectors for a pixel is electrically isolated from each other photodetector in the array of photodetectors. A microlens is disposed over the array of photodetectors for the pixel. The pixel readout circuit includes, per pixel, a shared readout circuit associated with the array of photodetectors for the pixel and a set of charge transfer transistors. Each charge transfer transistor is operable to connect a photodetector in the array of photodetectors to the shared readout circuit.

FIELD

The described embodiments relate generally to a device having a cameraor other image capture device. More particularly, the describedembodiments relate to an image capture device, pixel, and method ofoperating an image capture device or pixel, that provides improved phasedetection auto-focus (PDAF) performance for a device having a camera orother image capture device.

BACKGROUND

Cameras and other image capture devices often use an image sensor, suchas a charge-coupled device (CCD) image sensor or a complementarymetal-oxide-semiconductor (CMOS) image sensor, to capture an image. Insome cases, a camera or other image capture device may use multipleimage sensors, with the different image sensors having adjacent orinterlaced arrays of pixels.

Many cameras and other image capture devices include one or more opticalcomponents (e.g., a lens) that are configurable to focus light receivedor reflected from an image on the surface of an image sensor. Before orwhile capturing an image, the distance between the optical component(s)and image sensor (or a tilt or other parameters of the opticalcomponents or image sensor) may be adjusted to focus an image on theimage sensor. In some cases, macro (or rough) focusing may be performedfor an image sensor prior to capturing an image using the image sensor(e.g., using a macro focus mechanism adjacent the image sensor). Micro(or fine) focusing is often performed after acquiring one or more imagesusing the image sensor. Many cameras and other image capture devicesperform focusing operations frequently, and in some cases before orafter each image capture frame.

Focusing an image on an image sensor often entails identifying aperceptible edge between objects, or an edge defined by different colorsor brightness (e.g., an edge between dark and light regions), andbringing the edge into focus. Because low light conditions tend to mutethe edges in an image, focusing an image on an image sensor can beparticularly difficult under low light conditions, and an optimum focusmay take longer to achieve or not be possible.

SUMMARY

Embodiments of the systems, devices, methods, and apparatus described inthe present disclosure are directed to an image capture device, pixel,or method of operating an image capture device or pixel, that providesimproved PDAF performance for a device having a camera or other imagecapture device.

In a first aspect, the present disclosure describes an image capturedevice. The image capture device may include an imaging area and a pixelreadout circuit. The imaging area may include a plurality of pixels.Multiple pixels of the plurality of pixels may each include atwo-dimensional array of photodetectors and a microlens. Eachphotodetector in the array of photodetectors for a pixel may beelectrically isolated from each other photodetector in the array ofphotodetectors. A microlens may be disposed over the array ofphotodetectors for the pixel. The pixel readout circuit may include, perpixel, a shared readout circuit associated with the array ofphotodetectors for the pixel and a set of charge transfer transistors.Each charge transfer transistor may be operable to connect aphotodetector in the array of photodetectors to the shared readoutcircuit.

In another aspect, the present disclosure describes a pixel. The pixelmay include an imaging area, a microlens, and a same color light filter.The imaging area may include a two-dimensional array of photodetectors,with each photodetector in the array of photodetectors beingelectrically isolated from each other photodetector in the array ofphotodetectors. The microlens may be disposed over the array ofphotodetectors. The microlens may include a light-receiving sideopposite the array of photodetectors. The light-receiving side of themicrolens may include a central portion and peripheral portion. Theperipheral portion of the microlens may be configured to redirect atleast a portion of light incident on the peripheral portion toward acorresponding peripheral portion of the imaging area. The same colorlight filter may be disposed over the array of photodetectors.

In still another aspect of the disclosure, a method of determining afocus setting for an image capture device is described. The imagecapture device may include an image sensor having a plurality of pixels.The plurality of pixels may include multiple pixels that each include atwo-dimensional array of photodetectors disposed under a microlens. Eachphotodetector in the array of photodetectors may be electricallyisolated from each other photodetector in the array of photodetectors.The method may include capturing one or more images using a first focussetting for the image capture device; analyzing horizontal phasedetection signals output from a first set of the multipole pixels whilecapturing the one or more images; analyzing vertical phase detectionsignals output from a second set of the multiple pixels while capturingthe one or more images; and adjusting the first focus setting to asecond focus setting based on the horizontal phase detection signalanalysis and the vertical phase detection signal analysis.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIGS. 1A-1B show front and rear views of an electronic device thatincludes one or more image capture devices (e.g., cameras);

FIG. 2 shows an example embodiment of a camera, including an imagesensor, a lens, and an auto-focus mechanism;

FIG. 3 shows an example of an image that may be captured by a camera;

FIG. 4 shows a plan view of one example of an image sensor;

FIG. 5 shows an example imaging area (e.g., a plan view) of a pixel inan image sensor;

FIG. 6 shows an example cross-section of the pixel shown in FIG. 5;

FIG. 7 shows a simplified schematic of a pixel usable in an imagesensor;

FIG. 8 shows a pixel configured for detection of horizontal edge focus;

FIG. 9 shows a pixel configured for detection of vertical edge focus;

FIG. 10A-10C show an imaging area of an image sensor, in which thepixels of the image sensor are arranged in accordance with a Bayerpattern (i.e., a 2×2 pattern including red pixels and blue pixels alongone diagonal, and green pixels along the other diagonal);

FIG. 11 shows a method of determining a focus setting for an imagecapture device that includes an image sensor having a plurality ofpixels; and

FIG. 12 shows a sample electrical block diagram of an electronic device.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following description is not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

The present disclosure relates to an image capture device, pixel, andmethod of operating an image capture device or pixel, that providesimproved PDAF performance for a device having a camera or other imagecapture device.

In some cases, PDAF pixels (i.e., pixels configured to collect PDAFinformation) may have a metal shield configuration. A metal shield pixelmay include a microlens that focuses incoming light on a photodiode,which photodiode in turn converts photons into electron (or hole) pairs.The collected electrons (for electron collection devices) or holes (forhole collection devices) may be converted into an analog voltage througha pixel source follower (SF) transistor amplifier. The analog voltagemay then be converted to a digital signal by an analog-to-digitalconverter (ADC). A metal shield (e.g., a Tungsten (W) or Copper/Aluminum(Cu/Al) metal shield) may cover half of the photodiode (e.g., a lefthalf or a right half). For a left-shielded pixel, light fromleft-incident angles is blocked by the metal shield, and only lightapproaching the pixel from right-incident angles is received by thephotodiode. A right-shielded pixel functions in the opposite manner. Theangular sensitivity of left and right metal shield pixels can be used togenerate PDAF information.

Because the signal (e.g., the analog voltage or digital signal)generated by a metal shield pixel will be much lower than the signalgenerated by an unshielded (or regular) pixel, metal-shielded pixelsneed to be treated as defective pixels, and their signals need to becorrected before being used to generate an image. To minimize the effectthat signal correction may have on image quality, metal shield pixels(or pairs of left/right-shielded pixels) may be sparsely distributedover the surface of an image sensor. That is, a relatively small numberof an image sensor's pixels (e.g., 3-4%) may be configured as left orright-shielded pixels. In one example, for every eight rows and eightcolumns of pixels (e.g., for every block of 64 pixels in a pixel array),one left-shielded pixel and one right-shielded pixel may be provided.

At a vertical edge within an image (e.g., at an edge defined by aperceptible edge between objects, or at an edge defined by differentcolors or brightness (e.g., an edge between dark and light regions)),left and right-shielded pixels will have disparate signals (e.g.,signals not matched in magnitude and/or polarity) when an image is notin focus, but will have well-matched signals when an image is in focus.The signals of left and right-shielded pixels therefore provide PDAFinformation that can be used by an auto-focus (AF) mechanism to adjustthe position of one or more optical components (e.g., a lens) or animage sensor, and thereby adjust the focus of an image on the imagesensor. In some cases, an image may be brought into focus based on aPDAF information obtained during a single image capture frame. Byanalyzing PDAF information obtained during each image capture frame,images may be quickly and continuously focused on an image sensor.

In some embodiments, left and right-shielded pixels may be fabricatedwithout metal shields by placing both pixels adjacent one another undera single microlens. Each pixel has its own photodiode, and there may beimplant isolation or physical trench isolation between the photodiodesof the two pixels. Because of the nature (e.g., curvature) of themicrolens, light from left-incident angles is received mainly by theleft-side pixel, and light from right-incident angles is received mainlyby the right-side pixel. As a result, left and right-side pixels placedadjacent one another under a single microlens may function similarly toleft and right metal shielded pixels. In a Bayer pattern pixelconfiguration (i.e., a repetitive 2×2 pattern including red pixels andblue pixels along one diagonal, and green pixels along the otherdiagonal), one blue pixel in every 8×8 block of pixels may be replacedby a green pixel (or may be modified to function as a green pixel), sothat two adjacent green pixels may be placed under a single microlens toprovide PDAF information. The signals of both pixels need to becorrected before being used to generate an image.

Because the signals provided by metal shield pixels, or the signalsprovided by adjacent pixels under a microlens, need to be correctedbefore being used to generate an image, the density of such pixels maybe kept low. However, this provides limited PDAF information, which inturn degrades AF performance (especially in low light conditions). Toimprove PDAF performance, each pixel in a pixel array may be dividedinto left and right sub-pixels, and PDAF information may be obtainedfrom each pixel. Also, because all pixels are implemented in a similarmanner, the sub-pixel signals for each pixel may be combined in asimilar way, or signal corrections may be made to each pixel in asimilar way, to increase the confidence level that pixel signals arebeing generated or corrected appropriately (especially in low lightconditions). However, the PDAF information provided by such a pixelarray (and by all pixel arrays using metal shield pixels or adjacentpixels under a single microlens) bases image focus entirely on verticaledges. For an image containing few vertical edges or more horizontaledges, or for an image acquired under a low light condition, PDAFperformance may suffer. For example, it may be difficult or impossibleto focus an image on an image sensor, or it may take longer than desiredto focus an image on an image sensor.

The present disclosure describes a pixel having a 2×2 array ofsub-pixels (e.g., photodetectors) disposed under a microlens. In someembodiments, the entirety of a pixel array may incorporate such pixels.The pixels can be used, in various embodiments or configurations, toprovide PDAF information based on edges having more than one orientation(e.g., vertical and horizontal edges), to improve PDAF performance(especially in low light conditions), to reduce or eliminate the needfor signal correction, or to increase the resolution of an image sensor.

In one embodiment, a pixel described herein may include an imaging areaand a microlens, and may be associated with a set of charge transfertransistors and a shared readout circuit. The imaging area may include atwo-dimensional array of photodetectors, with each photodetector (oreach photodetector in a subset of photodetectors) being electricallyisolated from each other photodetector. The microlens may be disposedover the array of photodetectors. The shared readout circuit may beassociated with the array of photodetectors, and each charge transfertransistor may be operable to connect a photodetector in the array ofphotodetectors to the shared readout circuit. In some examples, chargeintegrated by two or four photodetectors may be read out of the pixelsimultaneously and summed by the shared readout circuit. In someexamples, charge integrated by different pairs of photodetectors may beread out of the pixel sequentially. In some examples, the pair ofphotodetectors for which charge is read out and summed may bereconfigured between image capture frames. In some examples, the chargeintegrated by each photodetector of the pixel may be independently read,or the charge integrated by all photodetectors of the pixel may be readout and summed.

These and other embodiments are discussed below with reference to FIGS.1-12. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes only and should not be construed as limiting.

Directional terminology, such as “top”, “bottom”, “front”, “back”,“over”, “under”, “left”, “right”, etc. is used with reference to theorientation of some of the components in some of the figures describedbelow. Because components in various embodiments can be positioned in anumber of different orientations, directional terminology is used forpurposes of illustration only and is in no way limiting. The directionalterminology is intended to be construed broadly, and therefore shouldnot be interpreted to preclude components being oriented in differentways.

Referring now to FIGS. 1A-1B, there are shown front and rear views of anelectronic device 100 that includes one or more image capture devices(e.g., cameras). The electronic device 100 includes a first camera 102,a second camera 104, an enclosure 106, a display 110, an input/output(I/O) member 108, and a flash 112 or light source for the second camera104. Each of the first camera 102 and second camera 104 may beassociated with a respective image sensor. The electronic device 100 mayalso include one or more internal components (not shown) typical of acomputing or electronic device, such as, for example, one or moreprocessors, memory components, network interfaces, and so on.

In the illustrated embodiment, the electronic device 100 is implementedas a smartphone. Other embodiments, however, are not limited to thisconstruction. Other types of computing or electronic devices which mayinclude a camera or image sensor include, but are not limited to, anetbook or laptop computer, a tablet computer, a digital camera, ascanner, a video recorder, a watch (or other wearable electronicdevice), a drone, a vehicle navigation system, and so on.

As shown in FIGS. 1A-1B, the enclosure 106 may form an outer surface orpartial outer surface and protective case for the internal components ofthe electronic device 100, and may at least partially surround thedisplay 110. The enclosure 106 may be formed of one or more componentsoperably connected together, such as a front piece and a back piece.Alternatively, the enclosure 106 may be formed of a single pieceoperably connected to the display 110.

The I/O member 108 may be implemented with any type of input or outputmember. By way of example only, the I/O member 108 may be a switch, abutton, a capacitive sensor, or other input mechanism. The I/O member108 allows a user to interact with the electronic device 100. Forexample, the I/O member 108 may be a button or switch to alter thevolume, return to a home screen, and the like. The electronic device mayinclude one or more input members or output members, and each member mayhave a single input, output, or I/O function, or some members may havemultiple I/O functions. In some embodiments, the I/O member 108 may beincorporated into the display 110, the first camera 102, or an audio I/Omember.

The display 110 may be operably or communicatively connected to theelectronic device 100. The display 110 may be implemented as anysuitable type of display, such as a high resolution display or an activematrix color liquid crystal display (LCD). The display 110 may provide avisual output for the electronic device 100 or function to receive userinputs to the electronic device 100 (or provide user outputs from theelectronic device 100). For example, the display 110 may display imagescaptured by the first camera 102 or the second camera 104. In someembodiments, the display 110 may include a multi-touch capacitivesensing touchscreen that is operable to detect one or more user inputs.

FIG. 2 shows an example embodiment of an image capture device (e.g., acamera 200), including an image sensor 202, a lens 204, and anauto-focus mechanism 206. In some embodiments, the components shown inFIG. 2 may be associated with the first camera 102 or the second camera104 shown in FIGS. 1A-1B.

The image sensor 202 may include a plurality of pixels, such as aplurality of pixels arranged in a two-dimensional array. Multiple ones(or all) of the pixels may each include a two-dimensional array ofsub-pixels (e.g., a 2×2 array of sub-pixels), with each sub-pixelincluding a photodetector. Having a majority (or more significantly atleast 80%, and preferably all) of the pixels configured to include a 2×2array of sub-pixels can help improve PDAF performance and/or reduce oreliminate the need to correct the outputs of PDAF-capable pixels inrelation to the outputs of other pixels. The sub-pixels (orphotodetectors) associated with a pixel may be electrically isolatedfrom each other, but disposed under a shared microlens for the pixel.

The lens 204 may be adjustable with respect to the image sensor 202, tofocus an image of a scene 208 on the image sensor 202. In someembodiments, the lens 204 may be moved with respect to the image sensor202 (e.g., moved to change a distance between the lens 204 and the imagesensor 202, moved to change an angle between a plane of the lens 204 anda plane of the image sensor 202, and so on). In other embodiments, theimage sensor 202 may be moved with respect to the lens 204.

In some embodiments, the auto-focus mechanism 206 may include (or thefunctions of the auto-focus mechanism 206 may be provided by) aprocessor. The auto-focus mechanism 206 may receive signals from theimage sensor 202 and, in response to the signals, adjust a focus settingof the camera 200. In some embodiments, the signals may include PDAFinformation. The PDAF information may include both horizontal phasedetection signals and vertical phase detection signals. In response tothe PDAF information (e.g., in response to an out-of-focus conditionidentified from the PDAF information), the auto-focus mechanism 206 mayadjust a focus setting of the camera 200 by, for example, adjusting arelationship between the image sensor 202 (or plurality of pixels) andthe lens 204 (e.g., by adjusting a physical position of the lens 204 orthe image sensor 202).

Referring now to FIG. 3, there is shown an example of an image 300 thatmay be captured by an image capture device, such as one of the camerasdescribed with reference to FIG. 1A-1B or 2. The image 300 may include anumber of objects 302, 304 having edges 306, 308 oriented in one or moredirections. The edges 306, 308 may include perceptible edges betweenobjects, or edges defined by different colors or brightness (e.g., anedge between dark and light regions). In some embodiments, the cameramay detect a focus of both a first set of edges (e.g., horizontal edges)and a second set of edges (e.g., vertical edges, or edges that areorthogonal to the first set of edges).

The focus of the first and second sets of edges may be detected in thesame or different image capture frames, using the same or differentpixels. In some cases, a focus of edges in the first set of edges may bedetected using a first subset of pixels configured to detect a focus ofhorizontal edges, in a same frame that a focus of edges in the secondset of edges is detected by a second subset of pixels configured todetect a focus of vertical edges. In another frame, a focus of edges inthe second set of edges may be detected by the first subset of pixels,and a focus of edges in the first set of edges may be detected by thesecond subset of pixels. In other cases, a focus of edges in the firstset may be detected by up to all of the pixels in an image sensor in afirst image capture frame, and a focus of edges in the second set may bedetected by up to all of the pixels in the image sensor in a secondimage capture frame. A focus of edges may be detected based on a phasedifference (e.g., magnitude and polarity of the phase difference) inlight captured by different sub-pixels (e.g., different photodetectors)associated with a pixel.

In some embodiments, a single pixel in a pixel array (and in some cases,some or each of the pixels in the pixel array, or each of the pixels ina subset of pixels in the pixel array) may be reconfigured between imagecapture frames, or at other times, to produce a signal usable fordetecting the focus of a horizontal edge, a vertical edge, or a diagonaledge. In some embodiments, all of the pixels in a pixel array (or all ofthe pixels used to capture a particular image) may be employed in thedetection of edge focus information for an image.

FIG. 4 shows a plan view of one example of an image sensor 400, such asan image sensor associated with one of the image capture devices orcameras described with reference to FIGS. 1A-1B and 2. The image sensor400 may include an image processor 402 and an imaging area 404. Theimaging area 404 may be implemented as a pixel array that includes aplurality of pixels 406. The pixels 406 may be same colored pixels(e.g., for a monochrome imaging area 404) or differently colored pixels(e.g., for a multi-color imaging area 404). In the illustratedembodiment, the pixels 406 are arranged in rows and columns. However,other embodiments are not limited to this configuration. The pixels in apixel array may be arranged in any suitable configuration, such as, forexample, a hexagonal configuration.

The imaging area 404 may be in communication with a column selectcircuit 408 through one or more column select lines 410, and with a rowselect circuit 412 through one or more row select lines 414. The rowselect circuit 412 may selectively activate a particular pixel 406 orgroup of pixels, such as all of the pixels 406 in a certain row. Thecolumn select circuit 408 may selectively receive the data output from aselected pixel 406 or group of pixels 406 (e.g., all of the pixels in aparticular row).

The row select circuit 412 and/or column select circuit 408 may be incommunication with an image processor 402. The image processor 402 mayprocess data from the pixels 406 and provide that data to anotherprocessor (e.g., a system processor) and/or other components of a device(e.g., other components of the electronic device 100). In someembodiments, the image processor 402 may be incorporated into thesystem. The image processor 402 may also receive focus information(e.g., PDAF information) from some or all of the pixels, and may performa focusing operation for the image sensor 400. In some examples, theimage processor 402 may perform one or more of the operations performedby the auto-focus mechanism described with reference to FIG. 2.

FIG. 5 shows an example imaging area (e.g., a plan view) of a pixel 500in an image sensor, such as a pixel included in an image sensorassociated with one of the image capture devices or cameras describedwith reference to FIGS. 1A-1B and 2, or a pixel included in the imagesensor described with reference to FIG. 4. In some embodiments, somepixels in an image sensor, each pixel in an image sensor, or each pixelin a subset of pixels in an image sensor, may be configured as shown inFIG. 5.

The imaging area of the pixel 500 includes a two-dimensional array ofphotodetectors 502 or sub-pixels (e.g., an array of sub-pixels, witheach sub-pixel including a photodetector 502). In some embodiments, theimaging area may include a 2×2 array of sub-pixels or photodetectors(e.g., a set of photodetectors 502 arranged in two rows and twocolumns). For example, the array may include a first photodetector 502 aand a second photodetector 502 b arranged in a first row, and a thirdphotodetector 502 c and a fourth photodetector 502 d arranged in asecond row. The first photodetector 502 a and the third photodetector502 c may be arranged in a first column, and the second photodetector502 b and the fourth photodetector 502 d may be arranged in a secondcolumn.

Each photodetector 502 may be electrically isolated from each otherphotodetector 502 (e.g., by implant isolation or physical trenchisolation). A microlens 504 may be disposed over the array ofphotodetectors 502. An optional same color light filter (e.g., a redfilter, a blue filter, a green filter, or the like) may also be disposedover the array of photodetectors 502. In some examples, the light filtermay be applied to an interior or exterior of the microlens 504. In someexamples, the microlens may be tinted to provide the light filter. Insome examples, each of the photodetectors may be separately encapsulatedunder the microlens 504, and the light filter may be applied to or inthe encapsulant. In some examples, a light filter element may bepositioned between the photodetectors 502 and the microlens 504(although other configurations of the light filter may also beconsidered as being disposed “between” the photodetectors 502 and themicrolens 504).

The photodetectors 502 may be connected to a shared readout circuit(i.e., a readout circuit shared by all of the photodetectors 502associated with the pixel 500). A set of charge transfer transistors maybe operable to connect the photodetectors 502 to the shared readoutcircuit (e.g., each charge transfer transistor in the set may beoperable (e.g., by a processor) to connect a respective one of thephotodetectors 502 to, and disconnect the respective one of thephotodetectors 502 from, the shared readout circuit; alternatively, acharge transfer transistor may be statically configured toconnect/disconnect a pair of the photodetectors 502 to/from the sharedreadout circuit). In some cases, each charge transfer transistor may beoperated individually. In other cases, the charge transfer transistorsmay be statically configured for pair-wise operation.

FIG. 6 shows an example cross-section of the pixel 500 shown in FIG. 5.By way of example, the cross-section is taken through the first row ofphotodetectors 502 shown in FIG. 5. Cross-sections through the secondrow, the first column, and the second column may be configured similarlyto the cross-section shown in FIG. 6.

A first sub-pixel 600 a may include the photodetector 502 a, and asecond sub-pixel 600 b may include the photodetector 502 b. The firstand second photodetectors 502 a, 502 b may be formed in a substrate 602.The substrate 602 may include a semiconductor-based material, such as,but not limited to, silicon, silicon-on-insulator (SOI),silicon-on-sapphire (SOS), doped and undoped semiconductor regions,epitaxial layers formed on a semiconductor substrate, well regions orburied layers formed in a semiconductor substrate, or othersemiconductor structures.

The microlens 504 may be disposed over part or all of both of thephotodetectors 502 a, 502 b (as well as part or all of thephotodetectors 502 c and 502 d). The microlens 504 may be formed of anymaterial or combination of materials that is translucent to at least onewavelength of light. The microlens may have a light-receiving side 612opposite the array of photodetectors 502. The light-receiving side 612of the microlens 504 may include a central portion 608 and a peripheralportion 610. The peripheral portion 610 may be configured to redirect atleast a portion of light incident on the peripheral portion (e.g., thelight 606 a or light 606 c) toward a corresponding peripheral portion ofthe imaging area that includes the photodetectors 502 (e.g., the light606 a may be redirected toward the photodetector 502 a, and the light606 c may be redirected toward the photodetector 502 b). In someembodiments, the microlens 504 may have a convex-shaped or dome-shapedlight-receiving surface (or exterior surface).

The microlens 504 may be configured to focus incident light 606 receivedfrom different angles on different ones or both of the photodetectors502 a, 502 b. For example, light 606 a incident on the microlens 504from a left side approach angle may be focused more (or solely) on theleft side photodetector 502 a, and thus the left side photodetector 502a may accumulate more charge than the right side photodetector 502 b,making the signal response of the left side sub-pixel 600 a greater thanthe signal response of the right side sub-pixel 600 b. Similarly, light606 c incident on the microlens 504 from a right side approach angle maybe focused more (or solely) on the right side photodetector 502 b, andthus the right side photodetector 502 b may accumulate more charge thanthe left side photodetector 502 a, making the signal response of theright side sub-pixel 600 b greater than the signal response of the leftside sub-pixel 600 a. Light 606 b incident on the microlens 504 from thefront center (or top) of the microlens 504 may be focused on both of thephotodetectors 502 a, 502 b, making the signal response of the left andright side sub-pixels 600 a, 600 b about equal.

An optional same color light filter 604 (e.g., a red filter, a bluefilter, a green filter, or the like) may be disposed over each of thephotodetectors 502 a, 502 b (as well as the photodetectors 502 c and 502d).

Referring now to FIG. 7, there is shown a simplified schematic of apixel 700 (and associated shared readout circuit 704) usable in an imagesensor. In some embodiments, the pixel 700 may be an example of a pixelincluded in an image sensor associated with one of the image capturedevices or cameras described with reference to FIGS. 1A-1B and 2, or apixel included in the image sensor described with reference to FIG. 4,or the pixel described with reference to FIGS. 5-6. In some embodiments,some pixels in an image sensor, each pixel in an image sensor, or eachpixel in a subset of pixels in an image sensor, may be configured asshown in FIG. 7, and the shared readout circuit 704 for the pixel 700may be part of an overall pixel readout circuit for an image sensor.

The pixel 700 may include a two-dimensional array of photodetectors 702,with each photodetector 702 being selectively connectable to (anddisconnectable from) the shared readout circuit 704 by a respectivecharge transfer transistor in a set of charge transfer transistors 706.In some embodiments, the two-dimensional array of photodetectors 702 mayinclude a 2×2 array of photodetectors (e.g., an array of photodetectors702 arranged in two rows and two columns). For example, the array mayinclude a first photodetector 702 a (PD_TL) and a second photodetector702 b (PD_TR) arranged in a first row, and a third photodetector 702 c(PD_BL) and a fourth photodetector 702 d (PD_BR) arranged in a secondrow. The first photodetector 702 a and the third photodetector 702 c maybe arranged in a first column, and the second photodetector 702 b andthe fourth photodetector 702 d may be arranged in a second column. Asdescribed with reference to FIGS. 5 and 6, the photodetectors 702 may bedisposed (positioned) in a 2×2 array under a microlens.

The shared readout circuit 704 may include a sense region 708, a reset(RST) transistor 710, a readout transistor 712, and a row select (RS)transistor 714. The sense region 708 may include a capacitor thattemporarily stores charge received from one or more of thephotodetectors 702. As described below, charge accumulated by one ormore of the photodetectors 702 may be transferred to the sense region708 by applying a drive signal (e.g., a gate voltage) to one or more ofthe charge transfer transistors 706. The transferred charge may bestored in the sense region 708 until a drive signal applied to the reset(RST) transistor 710 is pulsed.

Each of the charge transfer transistors 706 may have one terminalconnected to a respective one of the photodetectors 702 and anotherterminal connected to the sense region 708. One terminal of the resettransistor 710 and one terminal of the readout transistor 712 may beconnected to a supply voltage (e.g., VDD) 514. The other terminal of thereset transistor 710 may be connected to the sense region 708, while theother terminal of the readout transistor 712 may be connected to aterminal of the row select transistor 714. The other terminal of the rowselect transistor 714 may be connected to an output line 716.

By way of example only, and in one embodiment, each of thephotodetectors 702 may be implemented as a photodiode (PD) or pinnedphotodiode, the sense region 708 may be implemented as a floatingdiffusion (FD) node, and the readout transistor 712 may be implementedas a source follower (SF) transistor. The photodetectors 702 may beelectron-based photodiodes or hole-based photodiodes. The termphotodetector is used herein to refer to substantially any type ofphoton or light detecting component, such as a photodiode, pinnedphotodiode, photogate, or other photon sensitive region. Additionally,the term sense region, as used herein, is meant to encompasssubstantially any type of charge storing or charge converting region.

In some embodiments, the pixel 700 may be implemented using additionalor different components. For example, the row select transistor 714 maybe omitted and a pulsed power supply may be used to select the pixel.

When an image is to be captured, an integration period for the pixelbegins and the photodetectors 702 accumulate photo-generated charge inresponse to incident light. When the integration period ends, theaccumulated charge in some or all of the photodetectors 702 may betransferred to the sense region 708 by sequentially or simultaneouslyapplying drive signals to (e.g., by pulsing gate voltages of) the chargetransfer transistors 706. Typically, the reset transistor 710 is used toreset the voltage on the sense region 708 to a predetermined level priorto the transfer of charge from a set of one or more photodetectors 702to the sense region 708. When charge is to be read out of the pixel 700,a drive signal may be applied to the row select transistor 714 (e.g., agate voltage of the row select transistor 714 may be pulsed) via a rowselect line 718 coupled to row select circuitry, and charge from one,two, or any number of the photodetectors 702 may be read out over anoutput line 716 coupled to column select circuitry. The readouttransistor 712 senses the voltage on the sense region 708, and the rowselect transistor 714 transfers an indication of the voltage to theoutput line 716. The column select circuitry may be coupled to an imageprocessor, auto-focus mechanism, or combination thereof.

In some embodiments, a processor may be configured to operate the set ofcharge transfer transistors 706 to simultaneously transfer charge frommultiple photodetectors 702 (e.g., a pair of photodetectors) to thesense region 708 or floating diffusion node. For example, the gates offirst and second charge transfer transistors 706 a (TX_A) and 706 b(TX_B) (i.e., the charge transfer transistors of the first row) may besimultaneously driven to transfer charges accumulated by the first andsecond photodetectors 702 a, 702 b to the sense region 708, where thecharges may be summed. After reading the summed charge out of the pixel700, the gates of third and fourth charge transfer transistors 706 c(TX_C) and 706 d (TX_D) (i.e., the charge transfer transistors of thesecond row) may be simultaneously driven to transfer charges accumulatedby the third and fourth photodetectors 702 c, 702 d to the sense region708, where the charges may be summed. This summed charge may also beread out of the pixel 700. In a subsequent frame of image capture, thegates of the first and third charge transfer transistors 706 a and 706 c(i.e., the charge transfer transistors of the first column) may besimultaneously driven to transfer charges accumulated by the first andthird photodetectors 702 a, 702 c to the sense region 708. After readingthis charge out of the pixel 700, the gates of the second and fourthcharge transfer transistors 706 b and 706 d (i.e., the charge transfertransistors of the second column) may be simultaneously driven totransfer charges accumulated by the second and fourth photodetectors 702b, 702 d to the sense region 708. This charge may also be read out ofthe pixel 700. Additionally or alternatively, charge accumulated by thephotodetectors 702 may be read out of the pixel 700 individually, orcharges accumulated by any combination (including all) of thephotodetectors 702 may be read out of the pixel 700 together, or chargesaccumulated by the photodetectors 702 along a left or right-slopingdiagonal may be read out of the pixel 700 together.

When charges accumulated by different photodetectors 702 are read out ofthe pixel 700 individually, the charges may be summed in various ways,or a processor may interpolate between the values read out of the samecolored sub-pixels in different pixels of a pixel array to generate animage having an effective 4× resolution for the pixel array.

In some embodiments, a shared readout circuit per pixel may beconfigured differently for different pixels in a pixel array. Forexample, in a potentially lower cost image sensor, or in an image sensorimplemented using front side illumination (FSI) technology, a singlecharge transfer transistor may be coupled to a pair of photodetectors,and may be operated by a processor to simultaneously read charges outof, and sum charges, integrated by a pair of photodetectors. Forexample, in one pixel of an image sensor, a single charge transfertransistor could replace both of the charge transfer transistors 706 aand 706 b and connect both of the photodiodes 702 a and 702 b to theshared readout circuit 704, and another charge transfer transistor couldreplace both of the charge transfer transistors 706 c and 706 d andconnect both of the photodiodes 702 c and 702 d to the shared readoutcircuit 704. Similarly, in another pixel of the image sensor, a singlecharge transfer transistor could replace both of the charge transfertransistors 706 a and 706 c and connect both of the photodiodes 702 aand 702 c to the shared readout circuit 704, and another charge transfertransistor could replace both of the charge transfer transistors 706 band 706 d and connect both of the photodiodes 702 b and 702 d to theshared readout circuit 704.

In some embodiments, an image capture device, such as a camera, may notinclude a shutter, and thus an image sensor of the image capture devicemay be constantly exposed to light. When the pixel 700 is used in theseembodiments, the photodetectors 702 may have to be reset or depleted ofcharge before an image is captured (e.g., by applying drive signals(e.g., gate voltages) to the reset transistor 710 and charge transfertransistors 706). After the charge from the photodetectors 702 has beendepleted, the charge transfer transistors 706 and reset transistor 710may be turned off to isolate the photodetectors 702 from the sharedreadout circuit 704. The photodetectors 702 can then accumulatephoton-generated charge during a charge integration period.

FIG. 8 shows a pixel 800 configured for detection of horizontal edgefocus. The pixel 800 may be an example of a pixel included in an imagesensor associated with one of the image capture devices or camerasdescribed with reference to FIGS. 1A-1B and 2, or a pixel included inthe image sensor described with reference to FIG. 4, or the pixeldescribed with reference to any of FIGS. 5-7.

The imaging area of the pixel 800 includes a two-dimensional array ofphotodetectors 802 or sub-pixels (e.g., an array of sub-pixels with eachsub-pixel including a photodetector 802). For example, the array mayinclude a first photodetector 802 a and a second photodetector 802 barranged in a first row, and a third photodetector 802 c and a fourthphotodetector 802 d arranged in a second row. The first photodetector802 a and the third photodetector 802 c may be arranged in a firstcolumn, and the second photodetector 802 b and the fourth photodetector802 d may be arranged in a second column.

Each photodetector 802 may be electrically isolated from each otherphotodetector 802 (e.g., by implant isolation or physical trenchisolation). A microlens 804 may be disposed over the array ofphotodetectors 802. An optional same color light filter (e.g., a redfilter, a blue filter, a green filter, or the like) may also be disposedover the array of photodetectors 802.

The photodetectors 802 may be connected to a shared readout circuit(i.e., a readout circuit shared by all of the photodetectors 802associated with the pixel 800, as described, for example, with referenceto FIG. 7). A set of charge transfer transistors may be operable toconnect the photodetectors 802 to the shared readout circuit (e.g., eachcharge transfer transistor in the set may be operable (e.g., by aprocessor) to connect a respective one of the photodetectors 802 to, anddisconnect the respective one of the photodetectors 802 from, the sharedreadout circuit). In some cases, each charge transfer transistor may beoperated individually.

As indicated by the broken lines 806 a and 806 b, the charge transfertransistors may be operated (e.g., by a processor) to read a sum of thecharges accumulated by the first and second photodetectors 802 a, 802 bout of the pixel 800, and then operated to read a sum of the chargesaccumulated by the third and fourth photodetectors 802 c, 802 d out ofthe pixel 800. In some embodiments, the summed charges may be comparedto detect a phase difference in the charges, and to perform a PDAFoperation based on horizontal edge focus detection. The summed chargesmay also or alternatively summed to obtain a pixel value. In someembodiments, the summed charges may be summed without correction toobtain the pixel value.

FIG. 9 shows a pixel 900 configured for detection of vertical edgefocus. The pixel 900 may be an example of a pixel included in an imagesensor associated with one of the image capture devices or camerasdescribed with reference to FIGS. 1A-1B and 2, or a pixel included inthe image sensor described with reference to FIG. 4, or the pixeldescribed with reference to any of FIGS. 5-8.

The imaging area of the pixel 900 includes a two-dimensional array ofphotodetectors 902 or sub-pixels (e.g., an array of sub-pixels with eachsub-pixel including a photodetector 902). For example, the array mayinclude a first photodetector 902 a and a second photodetector 902 barranged in a first row, and a third photodetector 902 c and a fourthphotodetector 902 d arranged in a second row. The first photodetector902 a and the third photodetector 902 c may be arranged in a firstcolumn, and the second photodetector 902 b and the fourth photodetector902 d may be arranged in a second column.

Each photodetector 902 may be electrically isolated from each otherphotodetector 902 (e.g., by implant isolation or physical trenchisolation). A microlens 904 may be disposed over the array ofphotodetectors 902. An optional same color light filter (e.g., a redfilter, a blue filter, a green filter, or the like) may also be disposedover the array of photodetectors 902.

The photodetectors 902 may be connected to a shared readout circuit(i.e., a readout circuit shared by all of the photodetectors 902associated with the pixel 900, as described, for example, with referenceto FIG. 7). A set of charge transfer transistors may be operable toconnect the photodetectors 902 to the shared readout circuit (e.g., eachcharge transfer transistor in the set may be operable (e.g., by aprocessor) to connect a respective one of the photodetectors 902 to, anddisconnect the respective one of the photodetectors 902 from, the sharedreadout circuit). In some cases, each charge transfer transistor may beoperated individually.

As indicated by the broken lines 906 a and 906 b, the charge transfertransistors may be operated (e.g., by a processor) to read a sum of thecharges accumulated by the first and third photodetectors 902 a, 902 cout of the pixel 900, and then operated to read a sum of the chargesaccumulated by the second and fourth photodetectors 902 b, 902 d out ofthe pixel 900. In some embodiments, the summed charges may be comparedto detect a phase difference in the charges, and to perform a PDAFoperation based on vertical edge focus detection. The summed charges mayalso or alternatively summed to obtain a pixel value. In someembodiments, the summed charges may be summed without correction toobtain the pixel value. In some embodiments, a single pixel may beconfigured as shown in FIG. 8 for one image capture frame, andconfigured as shown in FIG. 9 for another image capture frame.

FIGS. 10A-10C show an imaging area 1000 of an image sensor, in which thepixels 1002 of the image sensor are arranged in accordance with a Bayerpattern (i.e., a 2×2 pattern including red pixels and blue pixels alongone diagonal, and green pixels along the other diagonal). The pixels1002 may be arranged in Bayer pattern rows 1006 a, 1006 b and Bayerpattern columns 1008 a, 1008 b. FIGS. 10A-10C also show each pixel 1002as having a 2×2 array of sub-pixels 1004, with each sub-pixel 1004including a photodetector, as described, for example, with reference toFIG. 5-9. FIGS. 10A-10C show different ways in which the readoutcircuits for the pixels 1002 may be configured during an image captureframe. In some embodiments, the imaging area 1000 may be an example ofan imaging area of an image sensor associated with one of the imagecapture devices or cameras described with reference to FIGS. 1A-1B and2, or the imaging area of the image sensor described with reference toFIG. 4, or an imaging area including a plurality of the pixels describedwith reference to any of FIGS. 5-9.

In FIG. 10A, the pixels 1002 in the first Bayer pattern row 1006 a ofthe imaging area 1000 are configured (or are operable) to detect a phasedifference (e.g., an out-of-focus condition) in a first set of edges ofan image (e.g., vertical edges), and the pixels 1002 in the second Bayerpattern row 1006 b are configured (or are operable) to detect a phasedifference in a second set of edges of the image (e.g., horizontaledges, or edges that are otherwise orthogonal to the first set ofedges). The configuration shown in FIG. 10A may be useful in that itsimplifies signal routing per Bayer pattern row 1006. However, improvedPDAF performance is only achieved by column.

In FIG. 10B, the pixels 1002 in the first Bayer pattern column 1008 a ofthe imaging area 1000 are configured (or are operable) to detect a phasedifference (e.g., an out-of-focus condition) in a first set of edges ofan image (e.g., vertical edges), and the pixels 1002 in the second Bayerpattern column 1008 b are configured (or are operable) to detect a phasedifference in a second set of edges of the image (e.g., horizontaledges, or edges that are otherwise orthogonal to the first set ofedges). The configuration shown in FIG. 10BA may be useful in that itsimplifies signal routing per Bayer pattern column 1008. However,improved PDAF performance is only achieved by row.

In FIG. 10C, a first set of the pixels 1002 in each Bayer pattern row1006 and Bayer pattern column 1008 of the imaging area 1000 isconfigured (or is operable) to detect a phase difference (e.g., anout-of-focus condition) in a first set of edges of an image (e.g.,vertical edges), and a second set of the pixels 1002 in the each Bayerpattern row 1006 and Bayer pattern column 1008 is configured (or isoperable) to detect a phase difference in a second set of edges of theimage (e.g., horizontal edges, or edges that are otherwise orthogonal tothe first set of edges). The configuration shown in FIG. 10C may beuseful in that it improves PDAF performance by row and column. However,signal routing is more complex over the configurations described withreference to FIGS. 10A-10B.

Pixels and pixel arrays configured as described in the presentdisclosure may be implemented using back side illumination (BSI)technology or FSI technology, though a BSI implementation may providemore metal routing options and better enable the charge collected byeach sub-pixel of a pixel to be separately read out of a pixel. Whenmetal routing options are limited, a particular pixel in a pixel arraymay be statically configured as a horizontal edge detection PDAF pixelor a vertical edge detection PDAF pixel.

Referring now to FIG. 11, there is shown a method 1100 of determining afocus setting for an image capture device that includes an image sensorhaving a plurality of pixels. Some or all of the pixels (e.g., eachpixel of multiple pixels) may include a two-dimensional array ofphotodetectors disposed under a microlens, with each photodetector ofthe array of photodetectors being electrically isolated from each otherphotodetector in the array of photodetectors. In some embodiments, themethod 1100 may be performed by one of the image capture devices orcameras described with reference to FIGS. 1A-1B and 2, or an imagecapture device or camera including the image sensor described withreference to any of FIGS. 4 and 10A-10C, or an image capture device orcamera including a plurality of the pixels described with reference toany of FIGS. 5-9.

At 1102, the method 1100 may include capturing one or more images usinga first focus setting for the image capture device. The operation(s) at1102 may be performed, for example, by the auto-focus mechanismdescribed with reference to FIG. 2, the image processor described withreference to FIG. 4, or the processor or image processor described withreference to FIG. 12.

At 1104, the method 1100 may include analyzing horizontal phasedetection signals output from a first set of the multiple pixels whilecapturing the one or more images. The operation(s) at 1104 may beperformed, for example, by the auto-focus mechanism described withreference to FIG. 2, the image processor described with reference toFIG. 4, or the processor or image processor described with reference toFIG. 12.

At 1106, the method 1100 may include analyzing vertical phase detectionsignals output from a second set of the multiple pixels while capturingthe one or more images. The operation(s) at 1106 may be performed, forexample, by the auto-focus mechanism described with reference to FIG. 2,the image processor described with reference to FIG. 4, or the processoror image processor described with reference to FIG. 12.

At 1108, the method 1100 may include adjusting the first focus settingto a second focus setting based on the horizontal phase detection signalanalysis and the vertical phase detection signal analysis. Theoperation(s) at 1108 may be performed, for example, by the auto-focusmechanism described with reference to FIG. 2, the image processordescribed with reference to FIG. 4, or the processor or image processordescribed with reference to FIG. 12.

In some embodiments of the method 1100, each of the first set ofmultiple pixels and the second set of multiple pixels may include theplurality of pixels (i.e., all of the pixels in the imaging area). Insome embodiments of the method 1100, at least a first subset of thehorizontal phase detection signals and at least a first subset of thevertical phase detection signals may be acquired in a single imagecapture frame (i.e., while capturing one images).

In some embodiments, the method 1100 may include modifying a pairing ofphotodetectors of at least one pixel in the multiple pixels (e.g.,modifying a sub-pixel pairing of at least one pixel in the multiplepixels). The modification may occur between a first image capture frameand a second image capture (i.e., between capturing a first image and asecond image). The pairing of photodetectors may determine a chargesumming that occurs during a read out of charges accumulated by a pixel.

FIG. 12 shows a sample electrical block diagram of an electronic device1200, which may be the electronic device described with reference toFIG. 1. The electronic device 1200 may include a display 1202 (e.g., alight-emitting display), a processor 1204, a power source 1206, a memory1208 or storage device, a sensor 1210, and an input/output (I/O)mechanism 1212 (e.g., an input/output device and/or input/output port).The processor 1204 may control some or all of the operations of theelectronic device 1200. The processor 1204 may communicate, eitherdirectly or indirectly, with substantially all of the components of theelectronic device 100. For example, a system bus or other communicationmechanism 1214 may provide communication between the processor 1204, thepower source 1206, the memory 1208, the sensor 1210, and/or theinput/output mechanism 1212.

The processor 1204 may be implemented as any electronic device capableof processing, receiving, or transmitting data or instructions. Forexample, the processor 1204 may be a microprocessor, a centralprocessing unit (CPU), an application-specific integrated circuit(ASIC), a digital signal processor (DSP), or combinations of suchdevices. As described herein, the term “processor” is meant to encompassa single processor or processing unit, multiple processors, multipleprocessing units, or other suitably configured computing element orelements.

It should be noted that the components of the electronic device 1200 maybe controlled by multiple processors. For example, select components ofthe electronic device 1200 may be controlled by a first processor andother components of the electronic device 1200 may be controlled by asecond processor, where the first and second processors may or may notbe in communication with each other.

The power source 1206 may be implemented with any device capable ofproviding energy to the electronic device 1200. For example, the powersource 1206 may be one or more batteries or rechargeable batteries.Additionally or alternatively, the power source 1206 may be a powerconnector or power cord that connects the electronic device 1200 toanother power source, such as a wall outlet.

The memory 1208 may store electronic data that may be used by theelectronic device 1200. For example, the memory 1208 may storeelectrical data or content such as, for example, audio and video files,documents and applications, device settings and user preferences, timingsignals, control signals, data structures or databases, image data, orfocus settings. The memory 1208 may be configured as any type of memory.By way of example only, the memory 1208 may be implemented as randomaccess memory, read-only memory, Flash memory, removable memory, othertypes of storage elements, or combinations of such devices.

The electronic device 1200 may also include one or more sensors 1210positioned substantially anywhere on the electronic device 1200. Thesensor(s) 1210 may be configured to sense substantially any type ofcharacteristic, such as but not limited to, pressure, light, touch,heat, movement, relative motion, biometric data, and so on. For example,the sensor(s) 1210 may include a heat sensor, a position sensor, a lightor optical sensor, an accelerometer, a pressure transducer, a gyroscope,a magnetometer, a health monitoring sensor, and so on. Additionally, theone or more sensors 1210 may utilize any suitable sensing technology,including, but not limited to, capacitive, ultrasonic, resistive,optical, ultrasound, piezoelectric, and thermal sensing technology.

The I/O mechanism 1212 may transmit and/or receive data from a user oranother electronic device. An I/O device may include a display, a touchsensing input surface such as a track pad, one or more buttons (e.g., agraphical user interface “home” button), one or more cameras, one ormore microphones or speakers, one or more ports such as a microphoneport, and/or a keyboard. Additionally or alternatively, an I/O device orport may transmit electronic signals via a communications network, suchas a wireless and/or wired network connection. Examples of wireless andwired network connections include, but are not limited to, cellular,Wi-Fi, Bluetooth, IR, and Ethernet connections.

The foregoing description, for purposes of explanation, uses specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not targeted to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. An image capture device, comprising: an imagingarea comprising a plurality of color-filtered pixels arranged in Bayerpattern rows and Bayer pattern columns, wherein: each color-filteredpixel comprises a two-dimensional array of photodetectors; eachphotodetector in an array of photodetectors is electrically isolatedfrom each other photodetector in the array of photodetectors; and adifferent microlens is disposed over each array of photodetectors; apixel readout circuit comprising, for each color-filtered pixel: ashared readout circuit associated with the array of photodetectors forthe color-filtered pixel; and a set of charge transfer transistors, eachcharge transfer transistor operable to connect a photodetector in thearray of photodetectors to the shared readout circuit; and a processorconfigured to: operate the sets of charge transfer transistors for thecolor-filtered pixels in a first Bayer pattern row to detect a firstphase difference in a first set of edges of an image; and operate thesets of charge transfer transistors for the color-filtered pixels in asecond Bayer pattern row to detect a second phase difference in a secondset of edges of the image, the first set of edges orthogonal to thesecond set of edges.
 2. The image capture device of claim 1 wherein eachshared readout circuit comprises a floating diffusion node.
 3. The imagecapture device of claim 2, wherein the processor is configured tooperate a first set of charge transfer transistors for a firstcolor-filtered pixel to simultaneously transfer charge from a pair ofphotodetectors of the first color-filtered pixel to a first floatingdiffusion node of the first color-filtered pixel, the pair ofphotodetectors selected from: a first pair of photodetectors in a firstrow; a second pair of photodetectors in a second row; a third pair ofphotodetectors in a first column; and a fourth pair of photodetectors ina second column.
 4. The image capture device of claim 1, furthercomprising: a lens, wherein the processor is configured to: identify anout-of-focus condition from at least one of the first phase differenceor the second phase difference; and adjust a relationship between theplurality of color-filtered pixels and the lens.
 5. The image capturedevice of claim 1, wherein each color-filtered pixel comprises a colorfilter disposed between the microlens and the array of photodetectorsfor the color-filtered pixel.
 6. The image capture device of claim 1,wherein a peripheral portion of each microlens has a convex shape. 7.The image capture device of claim 1, wherein: operating the sets ofcharge transfer transistors for the color-filtered pixels in the firstBayer pattern row to detect the first phase difference comprisesconfiguring a first set of charge transfer transistors for a first pixelto sum charges of a first pair of photodetectors aligned along a firstdirection; operating the sets of charge transfer transistors for thecolor-filtered pixels in the second Bayer pattern row to detect thesecond phase difference comprises configuring a second set of chargetransfer transistors for a second pixel to sum charges of a second pairof photodetectors aligned along a second direction.
 8. An image capturedevice, comprising: an imaging area comprising a plurality ofcolor-filtered pixels arranged in Bayer pattern rows and Bayer patterncolumns, wherein: each color-filtered pixel comprises a two-dimensionalarray of photodetectors; each photodetector in an array ofphotodetectors is electrically isolated from each other photodetector inthe array of photodetectors; and a different microlens is disposed overeach array of photodetectors; a pixel readout circuit comprising, foreach color-filtered pixel: a shared readout circuit associated with thearray of photodetectors for the color-filtered pixel; and a set ofcharge transfer transistors, each charge transfer transistor operable toconnect a photodetector in the array of photodetectors to the sharedreadout circuit; and a processor configured to: operate the sets ofcharge transfer transistors for the color-filtered pixels in a firstBayer pattern column to detect a first phase difference in a first setof edges of an image; and operate the sets of charge transfertransistors for the color-filtered pixels in a second Bayer patterncolumn to detect a second phase difference in a second set of edges ofthe image, the first set of edges orthogonal to the second set of edges.9. The image capture device of claim 8 wherein each shared readoutcircuit comprises a floating diffusion node.
 10. The image capturedevice of claim 9, wherein the processor is configured to operate afirst set of charge transfer transistors for a first color-filteredpixel to simultaneously transfer charge from a pair of photodetectors ofthe first color-filtered pixel to a first floating diffusion node of thefirst color-filtered pixel, the pair of photodetectors selected from: afirst pair of photodetectors in a first row; a second pair ofphotodetectors in a second row; a third pair of photodetectors in afirst column; and a fourth pair of photodetectors in a second column.11. The image capture device of claim 8, further comprising: a lens,wherein the processor is configured to: identify an out-of-focuscondition from at least one of the first phase difference or the secondphase difference; and adjust a relationship between the plurality ofcolor-filtered pixels and the lens.
 12. The image capture device ofclaim 8, wherein each color-filtered pixel comprises a color filterdisposed between the microlens and the array of photodetectors for thecolor-filtered pixel.
 13. The image capture device of claim 8, wherein aperipheral portion of each microlens has a convex shape.
 14. The imagecapture device of claim 8, wherein: operating the sets of chargetransfer transistors for the color-filtered pixels in the first Bayerpattern column to detect the first phase difference comprisesconfiguring a first set of charge transfer transistors for a first pixelto sum charges of a first pair of photodetectors aligned along a firstdirection; operating the sets of charge transfer transistors for thecolor-filtered pixels in the second Bayer pattern column to detect thesecond phase difference comprises configuring a second set of chargetransfer transistors for a second pixel to sum charges of a second pairof photodetectors aligned along a second direction.
 15. An image capturedevice, comprising: an imaging area comprising a plurality ofcolor-filtered pixels arranged in Bayer pattern rows and Bayer patterncolumns, wherein: each color-filtered pixel comprises a two-dimensionalarray of photodetectors; each photodetector in an array ofphotodetectors is electrically isolated from each other photodetector inthe array of photodetectors; and a different microlens is disposed overeach array of photodetectors; a pixel readout circuit comprising, foreach color-filtered pixel: a shared readout circuit associated with thearray of photodetectors for the color-filtered pixel; and a set ofcharge transfer transistors, each charge transfer transistor operable toconnect a photodetector in the array of photodetectors to the sharedreadout circuit; and a processor configured to: operate the sets ofcharge transfer transistors for a first set of color-filtered pixels ina first Bayer pattern column to detect a first phase difference in afirst set of edges of an image; operate the sets of charge transfertransistors for a second set of color-filtered pixels in the first Bayerpattern column to detect a second phase difference in a second set ofedges of the image, the first set of edges orthogonal to the second setof edges; operate the sets of charge transfer transistors for a thirdset of color-filtered pixels in a second Bayer pattern column to detectthe first phase difference in the first set of edges of the image; andoperate the sets of charge transfer transistors for a fourth set ofcolor-filtered pixels in the second Bayer pattern column to detect thesecond phase difference in the second set of edges of the image.
 16. Theimage capture device of claim 15 wherein each shared readout circuitcomprises a floating diffusion node.
 17. The image capture device ofclaim 16, wherein the processor is configured to operate a first set ofcharge transfer transistors for a first color-filtered pixel tosimultaneously transfer charge from a pair of photodetectors of thefirst color-filtered pixel to a first floating diffusion node of thefirst color-filtered pixel, the pair of photodetectors selected from: afirst pair of photodetectors in a first row; a second pair ofphotodetectors in a second row; a third pair of photodetectors in afirst column; and a fourth pair of photodetectors in a second column.18. The image capture device of claim 15, further comprising: a lens,wherein the processor is configured to: identify an out-of-focuscondition from at least one of the first phase difference or the secondphase difference; and adjust a relationship between the plurality ofcolor-filtered pixels and the lens.
 19. The image capture device ofclaim 15, wherein each color-filtered pixel comprises a color filterdisposed between the microlens and the array of photodetectors for thecolor-filtered pixel.
 20. The image capture device of claim 15, whereina peripheral portion of each microlens has a convex shape.